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Cotygodniowe seminarium badawcze
2020-11-18, godz. 14:15, online
Janusz Schmude (MIM UW)
Polynomial grammars with substitution
Polynomial grammars are grammars whose nonterminals generate tuples of integers (or elements of some ring in general) and productions use polynomial functions. They proved to be useful for proving decidability of equivalence of MSO transductions over strings and unordered trees and in general can be...
2020-11-04, godz. 14:15, Online
Mikołaj Bojańczyk (MIM UW)
Regular expressions for data words
I will discuss a proposal (one of many others) for regular expressions that use infinite alphabets. The regular expressions describe exactly the languages that can be recognised by nondeterministic orbit-finite automata (equivalently, nondeterministic register automata). The basic idea is to conside...
2020-10-21, godz. 14:15, online
Szymon Toruńczyk (Uniwersytet Warszawski (MIMUW))
A model-theoretic characterization of bounded twin-width
Twin-width is a graph parameter introduced recently in a series of papers by Bonnet, Geniet, Kim, Thomassé, and Watrigant. Among others, classes of bounded twin-width include all proper minor-closed classes, all classes of bounded tree-width or rank-width. We give a model-theoretic characterizat...
2020-10-14, godz. 14:00, online
Colin Geniet (ENS Paris-Saclay)
Twin-width is a graph complexity measure based on a notion of width of permutations by Guillemot and Marx [SODA '14]. Twin-width is defined through sequences of d-contractions, which witness that the twin-width is at most d. Notable classes of graphs with bounded twin-width are proper minor-close...
2020-06-24, godz. 14:15, 5050
Pierre Pradic (ENS Lyon)
Implicit automata in λ-calculi (joint work with Lê Thành Dũng (a.k.a. Tito) Nguyễn)
This work is part of an exploration of the expressiveness of the simply-typed λ-calculus (STLC) and related substructural variants (linear, affine, planar) using Church encodings of datatypes. More specifically, we are interested in the connection with automata theory for string trans...
2020-06-17, godz. 14:15, 5050
Jakub Gajarsky (Uniwersytet Warszawski)
Differential games for FO logic
I will introduce differential games for FO logic of graphs, a new variant of Ehrenfeucht-Fraisse games. These games are an attempt to extend currently used locality-based techniques for FO logic in a way which works naturally on non-sparse graphs. The hope is that the underlying idea can lea...
2020-06-10, godz. 14:15, Online seminar
Nathanael Fijalkow (CNRS, LaBRI)
Learning Probabilistic Context-Free Grammar
In this talk I will report on a joint work with Alexander Clark about learning (a subclass of) probabilistic context-free grammars published in the Transactions of the Association for Computational Linguistics. The objective of the talk is to introduce the main tool: matrix factorisation. ...
2020-06-03, godz. 14:15, Online seminar
Julian Salamanca (Uniwersytet Warszawski)
Lattices do not distribute over powerset
I will show that there is no distributive law of the free lattice monad over the powerset monad. The proof presented also works for other classes of lattices such as (bounded) distributive/modular lattices and also for some variants of the powerset monad such as the (nonempty) finite powerse...
2020-05-27, godz. 14:15, Online seminar
Joost Winter
From automata theory to coinduction with Haskell
In this talk I will approach a topic from classical automata theory, power series in a single input variable, from the point of view of coinductive specifications in the functional language Haskell, which are easy to specify and use due to Haskell's feature of lazy evaluation. In t...
2020-05-20, godz. 14:15, Online seminar
Vincent Michielini (Uniwersytet Warszawski)
Regular choices and uniformisations for countable domains (joint work with Michał Skrzypczak)
Considering the following question: given (in a sense which will be clarified in the talk) a countable totally ordered set D, on which condition(s) does there exist a choice function over D (i.e. a function f: P(D) -> D such that for all nonempty X subset of D, f(...
